Retainer ring structure for chemical-mechanical polishing machine

ABSTRACT

A retainer ring structure for a chemical-mechanical polishing (CMP) machine includes: a upper ring made of metal and having a plurality of bolt holes formed on the top surface thereof and coupled to a head of the CMP machine; and a lower ring made of resin and having a coupling groove formed in the center thereof and coupled to the upper ring, wherein the upper ring and the lower ring are coupled to each other such that the top surface of the upper ring and the circumferential top surface of the lower ring are positioned on the same plane.

BACKGROUND OF THE INVENTION

The present invention relates to a chemical-mechanical polishing (CMP) machine, and more particularly, to a retainer ring structure for CMP machine, which fixes the position of a silicon wafer during a CMP process, and easily couples a resin ring and a metal ring to not only reduce a mounting time of a retainer ring but also facilitate maintenance management, thereby increasing marketability.

With the increase in operating speed and integration degree of semiconductor devices, the increase in number of interconnection layers and the miniaturization of interconnection patterns in a multilayer interconnection structure have been required more and more. The multilayer interconnection technology is an important issue for a sub-micron process.

In particular, as a process margin for focus depth of an exposure system for realizing micro patterns shrinks with the advent of sub-0.35 μm process, a global planarization technique for a chip area is required to secure a sufficient focus depth.

Thus, a system referred to as chemical-mechanical polishing (CMP) machine is widely used to realize the global planarization technique. The CMP machine is essentially applied to a semiconductor device fabrication process, and research is being actively conducted on next-generation devices. The CMP machine is mainly applied to logic devices requiring multilayer interconnections to increase the operating speed of devices. However, as more and more memory devices employ a multilayer structure, application of the CMP machine to the memory devices is gradually increasing.

The CMP machine includes a retainer ring installed on a polishing head to fix a wafer, in order to perform a mechanical operation. The retainer ring is used to fix the position of a held wafer.

Since the retainer ring is formed of synthetic resin, the retainer ring has a low strength. Furthermore, a lot of time is required for a planarization process of the ring before the CMP process, and partial abrasion may occur due to the imbalance of force when a cover bolt is tightened.

Therefore, a ring formed of metal and synthetic resin may be used. In this case, however, liquid slurry supplied for chemical polishing may not be easily discharged from the retainer ring, and thus a surface scratch may occur during wafer polishing. Furthermore, since there are difficulties in washing the inside of the retainer ring, a surface scratch may occur due to foreign matters.

SUMMARY OF THE INVENTION

An embodiment of the present invention is directed to a retainer ring structure for a CMP machine, which fixes the position of a silicon wafer during a CMP process and easily couples a resin ring and a metallic ring to not only reduce a mounting time of a retainer ring but also facilitate maintenance management, thereby increasing marketability.

In accordance with an embodiment of the present invention, a retainer ring structure for a chemical-mechanical polishing (CMP) machine includes: a upper ring made of metal and having a plurality of bolt holes formed on the top surface thereof and coupled to a head of the CMP machine; and a lower ring made of resin and having a coupling groove formed in the center thereof and coupled to the upper ring, wherein the upper ring and the lower ring are coupled to each other such that the top surface of the upper ring and the circumferential top surface of the lower ring are positioned on the same plane.

The bottom of the upper ring made of metal may have a multi-stage structure, the coupling groove coupled to the bottom of the upper ring may have a multi-stage structure corresponding to the bottom of the upper ring, and the bottom of the upper ring may be coupled to the coupling groove through a fitting method or welding method.

In accordance with another embodiment of the present invention, a retainer ring structure for a CMP machine includes: an upper ring made of metal, having a plurality of bolt holes formed on the top surface thereof and coupled to a head of the CMP machine, having a center groove formed in the center thereof to a predetermined depth, and having a pair of edge protrusions formed at side surfaces of the center groove; and a lower ring made of resin, having a coupling groove formed in the center thereof and coupled to the upper ring, and having a center protrusion formed in the center of the coupling groove and inserted into the center groove of the upper ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates that a retainer ring structure according to an embodiment of the present invention is mounted on a CMP machine.

FIG. 2 is an exploded perspective view of the retainer ring structure according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of the retainer ring structure according to the embodiment of the present invention

FIG. 4 is an exploded perspective view of a retainer ring structure according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of the retainer ring structure according to the embodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Exemplary embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Throughout the disclosure, like reference numerals refer to like parts throughout the various figures and embodiments of the present invention.

FIG. 1 schematically illustrates that a retainer ring structure according to an embodiment of the present invention is mounted on a CMP machine, and the retainer ring structure is represented by reference numeral 10 in FIG. 1.

The CMP machine includes a main body 108 and a polishing head 112. The main body 108 includes a polishing platen 110 mounted on the top surface thereof and a polishing pad 106 installed on the top surface of the polishing platen 110.

The polishing head 112 includes a retainer ring structure 10 to fix a wafer 100, a polishing housing 102 having the structure 10 mounted thereon, and a rotating arm 104. The polishing housing 102 is rotated by the rotating arm 104.

The polishing platen 110 includes a polishing pad 106 provided on the top surface thereof, and the polishing pad 106 serves to polish the surface of the wafer 100 in a state where the polishing pad 106 is contacted with the surface of the wafer 100. The polishing platen 110 has a rotation driving shaft 114 formed at the bottom thereof and connected to a driving unit, and performs an orbital motion through the driving unit.

Referring to FIGS. 2 and 3, the retainer ring structure 10 includes an upper ring 12 made of metal and a lower ring 22 made of resin. The upper ring 12 has a plurality of bolt holes 16 formed on the top surface thereof and coupled to the head 112 of the CMP machine. The lower ring 22 has a coupling groove 18 formed in the center thereof and coupled to the upper ring 12. The upper ring 12 is coupled to the lower ring 22 such that the top surface of the upper ring 12 and the circumferential top surface of the lower ring 22 are positioned on the same plane.

At this time, the lower ring 22 may be made of a resin material which has more excellent mechanical property, higher chemical resistance, and higher thermal resistance than metals and other materials.

Although not illustrated in the drawings, it is obvious to those skilled in the art that the bottom of the upper ring 12 made of metal has a multi-stage structure, the coupling groove 18 coupled to the bottom of the upper ring 12 has a multi-stage structure corresponding to the bottom of the upper ring 12, and the bottom of the upper ring 12 may be coupled to the coupling groove 18 through a fitting method or welding method.

The upper ring 12 made of metal has a male screw thread formed on the bottom thereof, and the coupling groove 18 coupled to the bottom of the upper ring 12 has a female screw thread formed on the inner wall thereof. Thus, the upper ring 12 and the lower ring 22 may be screwed to each other.

FIG. 4 is an exploded perspective view of a retainer ring structure according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view of the retainer ring structure according to the embodiment of the present invention.

Referring to FIGS. 4 and 5, the retainer ring structure 30 includes an upper ring 32 made of metal and a lower ring 34 made of resin. The lower ring 34 has a coupling groove 18 coupled to the upper ring 32.

The upper ring 32 has a plurality of bolt holes 50 formed on the top surface thereof and coupled to the polishing head 112 of the CMP machine. Furthermore, since the lower ring 34 has a center groove 42 formed in the center thereof to a predetermined depth, the upper ring 32 has a pair of edge protrusions 48 formed at side surfaces of the center groove 42.

The lower ring 34 has the coupling groove 18 formed in the center thereof and coupled to the upper ring 32. Furthermore, the lower ring 34 has a center protrusion 36 formed in the center of the coupling groove 38 and inserted into the center groove 42 of the upper ring 32.

In order to more reliably couple the upper ring 32 and the lower ring 34, bolting may be performed. That is, the upper ring 32 and the center protrusion 36 of the lower ring 34 have coupling bolt holes 40 communicating with each other, and the upper ring 32 and the lower ring 34 are coupled through a coupling bolt 38.

According to the embodiments of the present invention, the metallic ring having the protrusion formed at the bottom thereof and the resin ring having the coupling groove coupled to the protrusion are reliably and easily coupled to increase the strength of the ring structure. Furthermore, the time required for planarizing a wafer may be reduced, and flatness may be improved.

Furthermore, as the imbalance of force based on the coupling between the metal ring and the resin ring is suppressed, partial abrasion may be prevented to increase durability. When the resin ring is worn out, the metallic ring may be reused.

While the present invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. 

What is claimed is:
 1. A retainer ring structure for a chemical-mechanical polishing (CMP) machine, comprising: a upper ring made of metal and having a plurality of bolt holes formed on the top surface thereof and coupled to a head of the CMP machine; and a lower ring made of resin and having a coupling groove formed in the center thereof and coupled to the upper ring, wherein the upper ring and the lower ring are coupled to each other such that the top surface of the upper ring and the circumferential top surface of the lower ring are positioned on the same plane.
 2. The retainer ring structure of claim 1, wherein the bottom of the upper ring made of metal has a multi-stage structure, the coupling groove coupled to the bottom of the upper ring has a multi-stage structure corresponding to the bottom of the upper ring, and the bottom of the upper ring is coupled to the coupling groove through a fitting method or welding method.
 3. The retainer ring structure of claim 1, wherein the upper ring made of metal has a male screw thread formed on the bottom thereof, the coupling groove coupled to the bottom of the upper ring has a female screw thread formed on an inner wall thereof, and the upper ring and the lower ring are screwed to each other.
 4. A retainer ring structure for a CMP machine, comprising: an upper ring made of metal, having a plurality of bolt holes formed on the top surface thereof and coupled to a head of the CMP machine, having a center groove formed in the center thereof to a predetermined depth, and having a pair of edge protrusions formed at side surfaces of the center groove; and a lower ring made of resin, having a coupling groove formed in the center thereof and coupled to the upper ring, and having a center protrusion formed in the center of the coupling groove and inserted into the center groove of the upper ring.
 5. The retainer ring structure of claim 4, wherein the upper ring and the center protrusion of the lower ring have coupling bolt holes communicating with each other such that the upper ring and the lower ring are coupled through the coupling bolts. 